1. Field of the Invention
The present invention relates to a composition with excellent pigment dispersibility.
2. Discussion of the Background
The state of dispersion of pigment in paints and molded products greatly affects their mechanical properties and workability and is also closely associated with qualities such as color, luster, etc., of the coat or molded product. Pigment and organic matrix often differ in surface energy, and if, for instance, the pigment is an inorganic material having a large surface energy, it has poor compatibility with the organic matrix of small surface energy, giving rise to the problem of agglomeration of pigment particles when said pigment and organic matrix are kneaded.
A solution to this problem is apply a surface treatment to the pigment particles. Such a surface treatment is usually made by using higher fatty acid(s), silane coupling agent(s), titanium coupling agent(s) or the like. However, in the case of using higher fatty acid(s), since they do not directly react on the functional groups oriented in a pigment particle surface, no covalent bonds are formed. Further, there usually exists surface water on inorganic material particles and therefore the surface treating agent is orientated on the particle surface with an interposition of the water layer, so that said agent is prone to separate. In the case of the conventional coupling agents, it is said that generally they form covalent bonds with the surface functional groups, and in case a surface treated pigment is filled in a resin, the silane type improves strength of the resin while the titanium type enhances working characteristics of, and dispersibility in, the resin.
There is known a variety of titanate type surface treating agents, which are classified according to the functional groups bonded to the titanium and the forms of its polymer backbones. As the polymers, there are used, for instance, straight chain types such as proposed in Japanese Patent Application Kokai (Laid-Open) No. 61-118348. It is said that use of a polymer is advantageous over use of monomer.
These surface treating agents are already applied to pigments, but further improvement in dispersibility of pigments that leads to higher performance and higher quality of the products are required.